1. Field of The Invention
The invention relates to a product, method and apparatus for producing separable fasteners of the hook and loop type, and more particularly for slitting and providing selvedge by ultrasonic means on such separable fasteners.
2. Description of The Prior Art
A selvedge (selvage) is the marginal edge portion on either side of a woven or flat knitted fabric so finished as to prevent raveling. Often it is woven of different or heavier threads than the actual fabric and oftentimes in a different weave pattern. The method for providing selvedge on woven fabric in the past was to set the loom or knitting machine up to weave or knit (as the case may be) the selvedge as the fabric was being manufactured This technique was always expensive and time consuming.
In particular, in separable fastener tapes of the hook and loop-type, the prior art techniques were cumbersome in that the final width of a woven or knitted separable fastener tape had to be selected at the actual weaving or knitting stage. This necessitated a large inventory of separable fasteners of numerous widths to be on hand to suit customer(s) requirements. Moreover, as is known, the stitch pattern of weaving and knitting machines are not sufficiently exacting as to maintain the desired width of the separable fastener tape within precise predetermined limits.
We have invented an apparatus and method for slitting and providing selvedge on fastener tapes along the selvedge thus provided. Thus our invention makes it possible to, in effect, stock all widths of tapes by merely stocking a single wide width tape, and thereafter providing individual selvedge and slitting according to the widths defined by customer needs, thereby providing widths of tape held within very close dimensional tolerances through the use of our apparatus.
Our invention also relieves a second problem found in prior methods of selvedging textile materials. The prior art methods produced a tape with a knitted or woven selvedge, but the tape would actually fluctuate in width along its length. This is caused by the unevenness of weaves or knits and small knots (or discontinuities) in the yarn or stitches. The present invention allows the tape width to be maintained within very small tolerances. This is possible because the selvedges and width are determined without the constraint of the knit or weave pattern.
The invention permits the quick production of narrow width tapes from a stock of broader width tapes. It also provides a continuous selvedge on the cut edges.